Anti-G suit inflation rate requirements

Area of Science:

• Aerospace Medicine
• Human Physiology
• G-force Tolerance

Background:

• Rapid-onset G-force exposure presents unique physiological challenges.
• Understanding G-tolerance is crucial for aircrew safety and performance.
• Existing G-tolerance metrics may not fully capture responses to high onset rates.

Purpose of the Study:

• To measure relaxed +Gz rapid-onset tolerances in human subjects.
• To investigate the effect of anti-G suit inflation timing on G-tolerance.
• To determine the feasibility of delayed anti-G suit inflation during high onset G-exposure.

Main Methods:

• Utilized a human-use centrifuge at the USAF School of Aerospace Medicine.
• Measured relaxed G-tolerances with and without inflated anti-G suits at varying onset rates (1 G.s-1 and 6 G.s-1).
• Assessed the impact of delayed anti-G suit inflation (mean delays of 3.3s and 4.2s) on tolerance criteria, including light-loss, during G-exposure and with the anti-G straining maneuver (AGSM).

Main Results:

• Relaxed G-tolerance was 0.2-0.3 G lower at 6 G.s-1 onset rates compared to 1 G.s-1 onset rates, indicating a potential 'very high onset G' tolerance.
• Delays of 3.3s in anti-G suit inflation did not alter relaxed G-tolerances at 6 G.s-1 onset rates.
• With a 4.2s delay, light-loss criteria occurred sooner. However, during AGSM at 7 G with 6 G.s-1 onset, a 2.8s delay was required before noticeable changes in light-loss criteria, while a 2.0s delay showed no change compared to zero delay.

Conclusions:

• High G-onset rates necessitate specific tolerance measurements beyond standard relaxed G-tolerance.
• Anti-G suit inflation can be delayed by at least 1 second without compromising protection during AGSM.
• These findings support optimizing anti-G suit inflation timing for enhanced aircrew protection and performance under rapid-onset G-forces.